from functools import lru_cache

def sorted_tuple(T):
    T=[t for t in sorted(T) if t!=1]
    return tuple(T)

@lru_cache(maxsize=None)
def greedy(A):
    if not A:
        return False

    for i,a in enumerate(A):
        if a>=2:
            b=a//2
            if a%2==0:
                T=A[:i]+A[i+1:]+(b,b)
                if not greedy(sorted_tuple(T)):
                    return True
            else:
                T=A[:i]+A[i+1:]+(b,b+1)
                if not greedy(sorted_tuple(T)):
                    return True
        if a>=3:
            c=a//3
            if a%3==0:
                T=A[:i]+A[i+1:]+(c,c,c)
                if not greedy(sorted_tuple(T)):
                    return True
            elif a%3==1:
                T=A[:i]+A[i+1:]+(c,c,c+1)
                if not greedy(sorted_tuple(T)):
                    return True
            else:
                T=A[:i]+A[i+1:]+(c,c+1,c+1)
                if not greedy(sorted_tuple(T)):
                    return True
    return False

N=int(input())

if N in [1,9,11,13,15,15,17,19,21,23]:
    print("B")
else:
    print("A")